I think of Sunlight Soap (a trademark originating in Britain) when people mention green soap, and I'm also sure that was what was being used in some hospitals many years ago. Sunlight soap is still available today in Britain and the previous "colonies": Australia, South Africa, etc. It is a so-called "pure" soap, supposed to be mild and gentle, and I rediscovered it as a great enema soap some years ago.
There is one big trick when using it, I discovered quite by accident. First, you dissolve about 10 grams (1/3 ounce) soap bar shavings in a cup of boiling water (300cc) and stir until the solution is clear. Now, if you use that solution straight away by diluting with more water in the enema bag to make about 2 quarts, the result is often unpleasant, irritating, even causing a bit of nausea if you're susceptible to it.
But here's the trick: After dissolving the shavings in the cup, you let it stand for a few hours (or overnight, if the enema is the next morning). Something amazing happens. The solution in the cup undergoes some form of transformation into an opaque, whitish-green gel-like substance, which has a snotty, slippery consistency. It gets quite "stiff" and has to be stirred up in the cup again to lower the viscosity. When you pour the cup into a mixing pitcher with more water for the enema, this gelly stuff sinks straight to the bottom. You then stir quite vigorously with a spoon (do not shake) to get an even spread throughout the solution, but you'll notice that the enema water is more of a "suspension" than a properly diluted solution. When left for too long, the soap/gel sinks to the bottom again, but you have enough time to set up the enema at leisure and get things flowing.
Now use THAT for an enema - the slippery consistency of the mix makes it creep around every corner of your bowel without the slightest discomfort when flowing in, passing any obstructive contents effortlessly. Retain for 10 minutes or so and experience a fantastic expulsion - equally slippery and very thorough. With no lingering discomfort afterwards (but I do a rinse anyway). Give it a try - and let us know how you experienced it!